A longitudinal survey of sleep habits in high school and college students is proposed with the following goals: to describe sleep habits across this age span; to assess longitudinal changes in sleep habits; to evaluate the interaction of sleep habits with global educational performance. A comprehensive survey of sleep habits and related variables will be performed yearly for four years in members of the class of 1987 attending local high schools and colleges. Data will be analyzed cross-sectionally and longitudinally, and aftee partialling out effects not specifically related to sleep, sleep variables will be related to percentile class rank. The prevalence of specific sleep disorders will be established from the sleep habits questionnaire surveys and documented with clinical findings and polysomnographic evaluations when possible. Volunteers whose questionnaire data indicate a specific sleep disorder will be paired along other variables with noncomplaining volunteers. Clinical evaluation, polysomnographic testing, and diagnosis using the Association of Sleep Disorders Centers classification system will be performed. In addition, therapeutic intervention will be assessed in specific cases. Finally, several specific sleep/waking schedules will be tested on subgroups of students with the goal of achieving guidelines for a rational sleep hygiene for adolescents. These schedules will be derived from previous experimental work and from the survey questionnaire data. Studies will be carried out in the Summer Sleep Laboratory using all-night, multiple sleep latency test, and performance test recording techniques.